I came to Messenger of Allah ﷺ with a cup of milk from Naqi' which had no cover over it, whereupon he said: Why did you not cover it? - even if you had covered it only with a stick. Abu Humaid said that he had been ordered that waterskins be tied during the night, and the doors be closed during the night. (Using translation from Muslim 2010a)
أَنَّهُ أَتَى النَّبِيَّ ﷺ بِقَدَحِ لَبَنٍ مِنَ النَّقِيعِ لَيْسَ بِمُخَمَّرٍ فَقَالَ النَّبِيُّ ﷺ لَوْلَا خَمَّرْتَهُ وَلَوْ بِعُودٍ تَعْرُضُهُ قَالَ أَبُو حُمَيْدٍ إِنَّمَا أَمَرَ النَّبِيُّ ﷺ بِالْأَسْقِيَةِ أَنْ تُوكَأَ وَبِالْأَبْوَابِ أَنْ تُغْلَقَ لَيْلًا وَلَمْ يَذْكُرْ زَكَرِيَّا قَوْلَ أَبِي حُمَيْدٍ بِاللَّيْلِ